why does my BMW X3 F25 (2011-2018) make a knocking noise when starting

Solution

1. Preparation

• Tools Required: OBD-II scanner, mechanic's stethoscope, socket set, torque wrench, engine oil, oil filter.
• Safety Warnings: Disconnect the battery before starting work on any electrical components.

2. Check Engine Oil Level

• Remove the dipstick and wipe it clean.
• Reinsert the dipstick fully, then remove it again to check the oil level.
• If low, top off with the appropriate engine oil as specified in the owner's manual.

3. Inspect and Replace Engine Oil

• Tools Required: Oil filter wrench, oil catch pan, funnel.
• Drain the old oil using the oil catch pan.
• Replace the oil filter with a new one.
• Refill the engine with new oil as per manufacturer specifications.

4. Inspect and Replace Timing Chain/Belt

• Remove necessary covers to access the timing chain/belt.
• Check for signs of wear or looseness.
• If worn, replace the timing chain/belt per manufacturer specifications, ensuring proper tension.

5. Check and Replace Engine Mounts

• Inspect engine mounts visually and by hand for signs of cracking or excessive wear.
• If damaged, remove bolts securing the mounts and replace them with new mounts.
• Torque the new mounts to the manufacturer’s specifications.

6. Reassemble and Test

• Reattach any components or covers that were removed during inspection and repairs.
• Reconnect the battery and start the engine to verify if the knocking noise persists.